Device providing assistance in the working of mechanical parts, including a guide track comprising multiple components

ABSTRACT

A device providing assistance in working of mechanical components, such as pipes, including a flange including parts assembled together such that they can pivot to occupy a closed position in which they are joined to one another. A clamping device can be actuated when the flange is closed. The flange also includes supporting elements used to connect rails to the parts with limited relative movement therebetween. Adjacent end faces of the rails include corresponding surfaces that are shaped to co-operate and establish a connection as the flange moves into the closed position. Each connection: guides the end faces in relation to one another and into a working position in which the rails form a guide track for the tools, and assists in maintaining the position when the clamping device is actuated.

The invention relates to a device for assisting with the working ofmechanical parts.

Although the invention falls within the scope of the working ofmechanical parts in general, such as for example valve bodies, profiledsections, rails and the like, the subject of particular interest here isthe working of tubes, notably pipes for use in the oil & gas industry(drilling, exploitation or transportation), purely for illustrativepurposes.

In fact, it will readily be understood that certain difficultiesencountered when working petroleum-carrying tubes may arise, inidentical form or in a slightly different guise, in the working of tubesfor use in other fields, on the one hand, and in the working ofmechanical parts of any kind, on the other hand. This is the case inparticular whenever these difficulties are linked, directly orindirectly, to a part of substantial bulk and/or mass, making it awkwardto move the part that is to be worked.

The term “work” is to be understood here in a very broad sense ascovering any operation carried out for industrial purposes on amechanical part, whether or not it results in a change of shape,appearance, surface finish nature, function or connection with othermechanical parts. For example, a measuring operation and more generallyany metrological operation is thus deemed to be work carried out on themechanical part.

Other work that may be carried out on mechanical parts includes, as anon-restrictive example, the welding together of parts, the grindingand/or cutting out of a part, taking radiographic images, or any testingoperation, particularly non-destructive.

For certain work it is sometimes more advantageous to attach the toolsto the tube or to the mechanical part rather than to a work station, forexample. This applies in particular to work that requires defining aframe with reference to the tube or the mechanical part. In the case oftubes, the welding of the ends of two tubes to one another, themeasurement and/or correction of the circularity of a tube or cutting atube into lengths may be mentioned by way of example.

In this case, a flange is provided which supports the tools and isattached around the tube or the mechanical part.

To ease its installation on the tube or part, the flange may be made intwo or more parts which are joined together with the possibility ofrelative movement in a common plane from an open position of the flangein which the parts are apart from each other, to a closed position ofthe flange in which these parts are continuous around the tube or thepart that is to be worked. A clamping device may be actuated, in theclosed position of the flange, to bring the parts in question intoabutment with, or close from, each other and ensure that this relativeposition of the parts is maintained in spite of the forces that may begenerated by the tubes, particularly by their displacement.

Most of the work to be carried out on tubes and on mechanical parts ingeneral requires precise and controlled movement of the tools relativeto the tube or mechanical part. In the case of parts shaped as bodies ofrevolution, such as tubes, for example, numerous types of work requirethe tool or tools to be moved around the periphery of the part.

As it is not very practical to rotate heavy and/or bulky tubes ormechanical parts, it is preferable to arrange for the tools to be movedrelative to the flange, which is attached to the tube or part withlimited movement possibilities.

As existing solutions have proved only partially satisfactory, theApplicant has set out to improve the situation.

The proposed apparatus comprises a flange having at least two partsjoined together with the ability to move relative to one another in acommon plane, up to a closed position of the flange in which the partsare joined together, a locking device that can be actuated in the closedposition of the flange to bring the said parts into mutual abutment, atleast two rails, and is notable in that it further comprises a set ofsupports by means of which each rail is connected to at least onerespective part of the flange with limited relative movementpossibilities, in that the adjacent end faces of two rails have matingsurfaces forming a connection by positive locking, this connection beingactive in the vicinity of the closed position, and in that eachconnection is arranged so as to guide the adjacent end faces relative toone another in a movement relative to said parts, to a working positionin which the rails form a guide path for one or more tools, and in orderto help keep these rails in mutual abutment, in this working position,when the locking device is actuated.

In the proposed apparatus, the rails are positioned relative to oneanother so as to create a path capable of supporting and guiding one ormore tools or tool holders, independently of the positioning of theparts forming the flange and supporting these rails.

In other words, the positioning of the rails is separate from thepositioning of the parts that form the flange. The parts forming theflange may be manufactured or machined with fairly large tolerances intheir dimensions. In practice, only the rails and in particular theirend faces connected by positive locking need to be precisionmanufactured or machined. It will be understood that the manufacturingcosts of the apparatus are significantly reduced.

Moreover, when considerable forces are applied to the flange, forexample in reaction to stress on the tube at a location remote from theflange, or to the forces generated by working (correcting thecircularity of the tube in particular), these forces are not transmittedto the guide path, owing to the fact that the rails are mounted onresilient supports. This means that the design measures taken to improvethe strength of the apparatus can be limited to the flange.

Furthermore, supposing that the forces in question cause deformation ofthe flange, this deformation does not affect either the positioning ofthe guide path relative to the flange or its shape. As a result, anintegral guide path is maintained, irrespective of the stress conditionsof the apparatus.

Optional features of the proposed apparatus which may be intended tocomplement, add to or replace the original features are described below:

-   -   The mating surfaces comprise two complementary surfaces in        mutual abutment in the working position.    -   Each rail has one or more guide surfaces and the connection        comprises an arrangement adapted to ensure continuity of these        guide surfaces in the working position.    -   The arrangement comprises at least one tongue projecting from        the end face of a rail and a groove provided in the adjacent end        face of a neighbouring rail, the tongue and the groove both        being of the appropriate dimensions to fit into one another        close to the position of closure of the flange.    -   The tongue has a portion whose cross-section becomes        progressively narrower towards its free end.    -   The arrangement comprises at least one stud projecting from the        end face of a rail and at least one recess formed in the        adjacent end face of a neighbouring rail, the stud and the        recess both being of the appropriate dimensions to fit into one        another close to the closed position of the flange.    -   The stud is at least partly hemispherical, or cylindrical, in        configuration.    -   The apparatus may further comprise a set of resilient parts        intercalated between the supports and their respective rails, in        which the resilient parts are deformed on actuation of the        locking device and are arranged so that this deformation        generates a contact pressure between the end surfaces of the        rails at a predefined minimum level.    -   The resilient parts are arranged so that the displacement of the        rails relative to the said parts of the flange takes place at        least in the vicinity of the position of closure with        deformation of at least some of said resilient parts.    -   The resilient parts are arranged so as to work with shear forces        when the locking device is actuated.    -   At least some of the resilient parts are in the form of a        cylinder made of resilient material, and each cylinder is        attached to one of the supports, on the one hand, and to a rail        and/or a part of said flange, on the other hand.    -   The flange is in the form of a flat crown.    -   The guide path is of annular configuration.

Further features and advantages of the invention will become apparentfrom a study of the description that follows, and of the accompanyingdrawings, wherein:

FIG. 1 shows an external clamp in a working situation, viewed inisometric perspective;

FIG. 2 shows an external clamp according to the invention, in a closedstate, viewed in isometric perspective;

FIG. 3 shows the clamp from FIG. 2, viewed in isometric perspective,from a different angle;

FIG. 4 shows the clamp of FIG. 3 viewed in section along a plane XYpassing through a point A looking in the direction Z;

FIG. 5 is analogous to FIG. 4, looking in the opposite direction todirection Z;

FIG. 6 is analogous to FIG. 2, with the clamp in an open state;

FIG. 7 shows a first frame element for the clamp in FIGS. 2 to 6, viewedin isometric perspective;

FIG. 8 shows a second frame element for the clamp in FIGS. 2 to 6,viewed in isometric perspective;

FIG. 9 shows a third frame element for the clamp in FIGS. 2 to 6, viewedin isometric perspective;

FIG. 10A shows a detail X from FIG. 8;

FIG. 10B shows a detailed part of FIG. 11, in a locked position of aclamp according to the invention, viewed in section;

FIG. 11 shows a detail XI from FIG. 6;

FIG. 12 shows, on its own, a reinforcement for the frame element in FIG.8, viewed in isometric perspective;

FIG. 13 shows, on its own, a centring stud, viewed in isometricperspective;

FIG. 14 shows, on its own, an alignment tongue, viewed in isometricperspective;

FIG. 15 shows an alternative embodiment of an external clamp accordingto the invention;

FIG. 16 is analogous to FIG. 7 for an alternative embodiment of externalclamp;

FIG. 17 is analogous to FIG. 8 for the alternative embodiment of FIG.16;

FIG. 18 is analogous to FIG. 9 for the alternative embodiment of FIG.16;

FIG. 19 is analogous to FIG. 11 for the alternative embodiment of FIG.16;

FIG. 20 is analogous to FIG. 13 for the alternative embodiment of FIG.16.

The attached drawings comprise elements of a specific nature and as suchmay serve not only to complement the invention but also to help todefine it, as necessary.

FIG. 1 shows a welding clamp of a known type 1, mounted externallystraddling respective end portions of two tubes 2, or pipes, intended tobe welded together.

The clamp 1 supports the tooling needed to produce a weld bead betweenthe ends of the tubes 3, i.e. a set of welding torches and a pluralityof supplementary tools which, when used in conjunction with one another,make it possible to carry out welding operations over the entire lengthof a pipeline.

Reference will now be made to FIGS. 2 to 6 to describe a clamp 3 capableof operating in the manner of the known welding clamp 1.

As shown, the clamp 3 is particularly well suited to welding operationsthat are to be carried out on tubes with a diameter of between 4 inchesand 24 inches, or even 64 or 100 inches. Consequently, the clamp 1 isadapted to fit the majority of the tubes used in the oil & gas industry,for extraction, drilling or even supplying.

However, the clamp 3 is by no means limited to this range of diameters,or to petroleum tubes.

On the other hand, the clamp 3 is not intended solely for weldingoperations and may not only include supplementary tooling such asmeasuring sensors, for example, but may also not be equipped withwelding torches, at least for certain applications.

However, in every case, the clamp 3 supports tools intended for workingon one or more tubes and is arranged so as to engage on the outer wallof these tubes.

The clamp 3 comprises a pair of flanges 5 each of which has theappearance of a flat crown and which are held fixedly opposite eachother by crosspieces 7 to form a frame.

Each flange 5 supports a clamping/positioning system intended for an endportion of a respective tube, the said system comprises a plurality ofclamping actuators 9 fixed to one side of the flange 5 so that theirheads extend radially, in a plane parallel to a main plane of the flange5, and in the central space thereof.

Each flange 5 may also support movement sensors (not shown) which makeit possible to monitor the respective movements of the clampingactuators 9 in synchronised manner.

Each flange 5 may also support a guide system intended for an endportion of a respective tube 2 comprising a plurality of supports (notshown), such as ball guides, fixed in a position such that they extendradially towards the centre of the flange 5, in a plane parallel to themain plane of the flange 5.

Thus equipped, each flange 5 makes it possible to move the central axisof its respective tube 2, up to a predefined position, or to displacethis tube 3 in its longitudinal direction. The clamp 3 allows for mutualalignment of the tubes 2 on which it is installed, either along theirouter diameter or along their inner diameter.

In other words, as described, the clamp 3 is adapted to be attached toend portions of tubes 2, to align these ends and to move them close toone another. The clamp 3 is able to support torches for welding theseends to one another.

Each flange 5 comprises a set of plates each extending over an angularsector of a crown, and connected to one another with the ability topivot relative to one another, in a common plane, from an open positionof the flange 5 in which the plates are spaced from one another, to aclosed position of the flange 5 in which the plates 13 are joinedtogether to form a crown.

In the embodiment shown, each flange 5 comprises a first plate 13A whichextends over an angular sector of about 180°, a second plate 13B and athird plate 13C both of which extend over an angular sector of about90°. The second plate 13B and the third plate 13C are each attached to arespective end of the first plate 13A via a hinge joint 11 the swivelaxis of which is substantially perpendicular to the main plane of thisplate.

Referring to FIG. 7, a first plate 13A of each flange 5 supports, ateach of its ends, a female part 15 of the hinge joint 11, this partcomprising two lugs 17 attached to this first plate 13A via a crosspiece7. The lugs 17 project from the crosspiece 7 so that their respectivemain planes extend parallel to the main plane of the first plate 13 a.

Each of the lugs 17 is drilled with an opening 19, the openings 19 ofthe same hinge joint 11 being mutually aligned, and extendingsubstantially perpendicularly to the main plane of the first plate 13A.

Referring to FIGS. 8 and 9, the second plate 13B and the third plate 13Cof each flange 5 each support, at one of their ends, a male part 23 ofthe hinge joint 11. This male part 23 comprises a journal 25 (not shownin FIG. 9) corresponding to the openings 19 in the female part 15 andsupported by a rotary bearing 27, for example in the form of a bushing.

The clamp 3 may be in an open position (shown in FIG. 6) in which theframe elements, each formed by assembling mating plates of the twoflanges 5 and the crosspieces 7 that connect them to one another, arespaced from one another, or a closed position (shown in FIGS. 2 to 5) inwhich these frame elements are combined to form a frame of cylindricalconfiguration with a circular base. The movement of the frame elementsrelative to one another takes place under the action of opening/closingactuators 28 fixed to each flange 5.

Each flange 5 supports a locking system, which can be actuated in theclosed position of the flange, which holds the first 13A, second 13B andthird 13C plates fixedly relative to one another. The locking systems ofthe flanges 5 may be controlled simultaneously or independently of oneanother, depending on the intended uses.

Each of the first 13A, second 13B and third 13C plates supports, on itscircular inner edge, a respective reinforcing structure in the form of agenerally profiled part which extends lengthwise along a portion of acircle corresponding to the angular sector of the plate to which it isattached, in this case by being bolted on.

In other words, each plate has a reinforcing structure in the generalshape of a curved profile the curvature of which corresponds to theinner edge of this plate.

Thus, each first plate 13A (FIG. 7) supports a first reinforcingstructure 29A, each second plate 13B (FIG. 9) supports a secondreinforcing structure 29B, and each third plate 13C (FIG. 8) supports athird reinforcing structure 29C.

Referring to FIGS. 7 to 9 and also to FIG. 12, each reinforcingstructure has at each end a widened portion 31, the widened portions 31of a structure being connected to one another by a profiled portion 32of essentially square cross-section. Each widened portion 31 hassurfaces mating with an adjacent widened portion 31 integral with aneighbouring plate, jointly forming a positively locking connectionacting in the vicinity of the closed position of the flange 5.

Each widened portion 31 has a first end surface 33 and a second endsurface 37, both of them planar, extending perpendicularly to the mainplane of the plate that supports them, and approximately radially withrespect to the latter.

This widened portion 31 also has a connecting surface 35, which is alsoplanar, connecting the first end surface 33 to the second end surface37.

By convention, the first end face 33 of a widened portion 31 is definedas the end surface located substantially on an extension of the profiledportion 32, while the second end face 37 is radially offset relative tothis profiled portion 32.

Referring moreover to FIGS. 10A, 10B and 11, the widened portions 31that cooperate in a same joint, i.e. which are arranged at adjacent endsof neighbouring plates of the same flange are arranged so as to engagemutually in the closed position of the flange, namely:

-   -   the first end surface 33 of a widened portion 31 is located        opposite the first end surface 33 of the other widened portion        31;    -   the second end surface 37 of a widened portion 31 is located        opposite the second end surface 37 of the other widened portion        31;    -   the connecting surfaces 35 of the two widened portions are        located opposite one another.

Each widened portion 31 has a respective bore 41 which is drilledsubstantially radially and opens onto the connecting surface 35 roughlycentrally.

When a flange 5 is open (see FIG. 10A for example), in each of thejoints of this flange, one of the bores 41 accommodates a locking pin 43of generally cylindrical shape with a circular base, fitting therein sothat the pin 43 can pivot about its longitudinal axis and move intranslation in a direction parallel to this axis. Each pin 43 is mountedon the rod of a respective locking actuator 45, the actuator being fixedto a corresponding plate. Preferably, a swivel connection is providedbetween the head of the locking actuator 45 and the pin 43 which itmoves.

When a flange 5 is in the closed position in one of the joints of thisflange, the widened portions 31 are mutually engaged, and the lockingactuators 45 can be actuated to move their respective locking pins 43until the latter partly projects into the bore 41 in an adjacent widenedportion 41 (see FIG. 10B for example). When all the locking pins 43 areengaged in the bores 41 of a flange 5, this flange 5 is in a lockedstate.

The mating bores 41 may be slightly offset relative to one another: thedistance separating the axis of one bore 41 from the second end surface37 of the same widened portion 31 may slightly differ from the distanceseparating the axis of the mating bore 41 from the mating second endsurface 37. Thus, the engagement of the pin 43 in the mating bore 41gives rise to a mutual contact pressure between at least some of thefirst and second 37 mating surfaces.

Here, the offset is such that it is ensured, in the locked position of aflange 5, that the contact pressure in question operates between thesecond end surfaces 37 of all the connections of this flange. This makesit possible to achieve a continuity of material between the differentreinforcing structures 29, thus improving the mechanical strength of theflange.

For example, the offset in question may be equal to a few hundredths ofa millimeter, for example 3. The first end surfaces 33 are machined withmanufacturing tolerances that ensure that there is integral contactbetween the second end surfaces 37, i.e. the first end surfaces 33 donot come to bear on one another when the flange 5 that they form islocked.

As described, the widened portions 31, the locking pins 43 and thelocking actuators 45 jointly fulfil a dual function, namely a functionof clamping a flange 5, bringing the plates that form it to abut on oneanother via second end surfaces 37, and a function of locking thisflange in the closed position.

On each occasion, a locking actuator 45, the pin 43 that it actuates anda pair of adjacent widened portions 41 form what may be referred to as alatch.

The second surfaces 37 form the mutual abutment surfaces of the first13A, second 13B and third 13C plates of the same flange against oneanother.

In the closed/locked position, the reinforcing structures of a flange 5extend jointly around a circle corresponding to the central edge of thisflange 5, and thus form what might be referred to as a force take-upring. Each of the first 29A, second 29B and third 29C structures ismechanically connected to one or more of the crosspieces 7 viareinforcing plates 48 which are fixed such that their main plane extendsradially and perpendicularly to the corresponding plate. Eachreinforcing plate 48 has a notched portion, at the end in this case,abutting substantially radially on a reinforcing structure. Reinforcingplates 48 are arranged at each of the adjacent ends of the second plate13B and the third plate 13C. These reinforcing plates 48, in thevicinity of their notched portion, come to bear, with a large mainsurface, against a mating surface of a widened portion 31. Optionally,additional reinforcing plates (not shown) may be provided, having acurved part that engages around a profiled portion 32 of a reinforcingstructure and bearing on the corresponding plate, thus further improvingthe strength of the flange 5, and thereby sparing the plates that makeup this flange. These plates can then be made with a reduced thickness.

The connecting surfaces 35 extend perpendicularly to the main plane ofthe plate that supports the corresponding reinforcing structure, and areinclined in this case so as to be remote from the inner circular edge ofthe flange 5, to prevent any interference with the opening/closing ofthe corresponding flange 5.

Referring to FIGS. 2 to 7, and to FIG. 11, one of the flanges 5 supportsa guide device for tools or for a tool-holder carriage. This guidedevice comprises a set of rails 49 each extending along a portion of acircle the angular amplitude of which corresponds to that of the platewhich supports it.

Each rail 49 is supported on its respective plate by a support plate 53extending in corresponding manner, against which it bears with a firstlarge surface. Each support plate 53 is in turn supported by a largesurface of the plate in question by columns 55 which are attached to alarge surface opposite a large surface bearing on the first largesurface of the corresponding rail 49.

Between each column 55 and the support plate 53 which it supports isinterposed a resilient part, in this case constructed in the form of acylinder 57 of resilient material, e.g. rubber. This permits limitedmovement of the rail according to six degrees of freedom. Each column 55provided with its resilient cylinder forms a resilient support by meansof which a rail 49 is at least partly connected to a plate of a flange5.

The cylinder 57 is a “silentbloc” made by the Belgian company Paulstra(registered trade mark). Flexible elements of different kinds (springs,Belleville washers or the like) may be used, instead of or in additionto the cylinders 57.

Each rail 49 is made in the form of a profiled section having a bodyportion 61 attached to its first large surface, and a guide portion 63adjacent to the body portion 61 and having a free large surface oppositethe first large surface. Here, the guide portion 63 is wider than thebody portion.

In the guide portion 63, the free large surface is bordered on bothsides by a respective guide surface 64, each in the form of two surfacesarranged in a V, so as to form a guide section for tools or tool-holdercarriages.

The adjacent ends of neighbouring rails 49 each have mating surfacesshaped to form a joint by positive locking acting in the vicinity of theclosed position of the flange 5.

Each positively locking joint comprises a centring stud 65 whichprojects from a flat end surface 66 arranged substantially radially of arail 49, and a centring opening 67 provided in a mating surface 66 of aneighbouring rail 49. The fit may be of the H7g6 type as defined in ISOstandards.

When a flange 5 is closed, the positively locking joint ensures that theadjacent end surfaces 66 of the neighbouring rails 49 are centred,relative to one another, guiding the rails 49 in question, in a movementrelative to the plate that supports them, to the extent permitted by thedeformation of the resilient cylinders 57, as far as a position in whichthey jointly form a guide path, which in this case is annular (see FIG.4).

Each positively locking joint further comprises an alignment tongue 69projecting from the flat end face 66 of a rail 49 and an alignmentgroove 71 provided in the mating surface of the adjacent face of aneighbouring rail 49. Here, each groove 71 is produced by providing arecess in the face of the support plate 53 in contact with the rail 49that is supported, over a corresponding end portion thereof.

When the flange 5 is closed the positively locking joint ensures thatthe rails 49 are aligned relative to one another, more precisely thattheir guide edges 64 are aligned, by guiding the rails 49 in question ina movement relative to the plate that supports them, to the extentpermitted by the deformation of the resilient cylinders.

The columns 55 project from the plates which support them, substantiallyperpendicularly to the main plane of these plates. The columns 55 areattached by a foot portion 73 to their respective plates and by a headportion 75 to a support plate 53 via a resilient cylinder 57. The feet73 are distributed in a circle with a slightly smaller diameter than thecircle in which the heads 75 are distributed.

Thus, when the clamping/locking device of the flange 5 is actuated, theresilient cylinders 57 operate with shear and generate a contactpressure of the flat end surfaces 66 against one another. Thus, aclosure system for the guide path is obtained which is indirectlycontrolled by the locking system of the flange 5, with a forced abutmentof the rails 49 against one another, which ensures that the guide pathhas the necessary integrity, even under conditions of loading of thispath, particularly by the tools or tool holders.

The resilient cylinders are selected, dimensioned and positioned so asto obtain a contact pressure of a predefined magnitude, which largelydepends on the mass of the tools and/or tool holders that are to beguided and, possibly, the forces that these tools exert on the guidepath, under operating conditions.

When a centring stud 65 is engaged in the corresponding opening 67, thepositioning of the end faces 66 relative to one another is ensured. Oncethe tongue 69 has engaged in the groove 71, the alignment of the guidesurfaces 64 of the different rails 49 is ensured.

Referring to FIG. 13, a stud 65 is of revolutionary shape and comprisesa cylindrical end portion 77 intended to be accommodated in a holeprovided on the end face 66 of a rail 49, and an adjacent hemisphericalportion 79, whose end opposite the cylindrical portion 77 has aflattened part 81.

Referring to FIG. 14, the tongue 69 is of generally flat and rectangularconfiguration, and comprises a portion of constant cross-section 83,intended to be trapped between the first large face of a rail 49 and thecorresponding support plate 53 in a recess provided on the correspondinglarge face of this support plate 53 on an end portion, and a portion 85the cross-section of which narrows progressively in a wedge shapetowards its free end, in width and thickness.

The double V-shaped profile makes it possible to support weldingtorches, for example, but applies to other tools. When the lockingsystem is closed, the rails 49 bear on one another with their end facesand thus provide a complete and precise circular guide for the tools andtool holders.

This ensures continuity of the guide surfaces 66 when the flange 5 is inthe closed position, as well as the correct positioning of these guidesurfaces, which are features essential to the production of a suitableguide path.

In fact, when there is even slight bending between two rails 49, thetools or tool holders jam when passing from one rail to the other.Analogously, offsetting of two rails would cause the tools or toolholders to jump when passing from one rail 49 to the other, resulting inwelding defects in particular or, more generally, lack of precision inthe working.

The columns 55 provided with their resilient cylinders 57 formresiliently deformable supports for the rail elements 49. Supports ofthis kind enable the rails to be adjusted relative to one another,independently of the adjustment of the plates forming the flange 5between them. This means that the plates in question can be machinedwith greater tolerances, preventing any deformations on the plates fromresulting in deformation of the guide path.

This ensures the guide path to be kept in the closed position, apartfrom the shearing operation of the resilient cylinders 57, by theclamping effect obtained using the locking device described. It shouldbe understood that this maintenance may be obtained whenever there is aclamping action of the plates against one another, whether by means of aspecific device, including devices of a different embodiment from theclamping/locking device described, a device which also provides adifferent primary function, or in some other way. The choice of theclamping device will depend chiefly on the contact pressure neededbetween the rails 49. It should be understood, on the one hand, that thestrength capabilities of the closure of the guide path depend to a largeextent on the clamping force of the plates against one another, and onthe other hand, the strength requirements of this closure may differaccording to the particular applications envisaged, and in particular asa function of the mass of the tools or tool holders being supported.

For example, the locking actuators also tend to clamp the plates againstone another. The opening/closing actuators too. The clamped stateresulting from some and/or others of these actuators may lead to asufficient strength of closure of the guide path, at least for certainapplications. In this case, the locking/clamping device described, whileadvantageous in that it imparts good rigidity to the flanges 5 whilekeeping their mass fairly low, appears to be optional. In other cases,the clamping effect obtained with the device described may proveinadequate and require additional closing means, including means mounteddirectly between the rails 49, for example by means of toggles.

The reinforcing structures described are advantageous in that they allowa flange 5 to be made very rigid without increasing its mass. However,in applications in which the phenomena linked to the mass of the flanges5 are of only limited importance, a similar degree of rigidity could beobtained by using thicker plates, for example.

Plates assembled by means of hinge joints are described, which allow theplates to pivot relative to one another. The invention is not limited tothis type of joint but encompasses all joints that would enable a set ofplates forming a flange to adopt a closed position and an open positionregardless of the relative movement permitted by these joints.

The annular guide path described hereinbefore is especially suited toworking parts shaped as bodies of revolution in particular. For workingmechanical parts of a different kind, or for work that does not requirethe tools to perform a complete revolution around the mechanical part,guide paths that are not closed may be envisaged, of any desired shape.

Reference will now be made to FIGS. 16 to 20 which show an alternativeembodiment of clamp 3 described above. This variant of clamp 3 presentsthe followings distinctive features which, where applicable, can combinewith the features described in relation with the clamp 3:

-   -   The mating surfaces of the adjacent end faces of neighbouring        rails (49) present a centring opening 87 in the shape of a        half-cylinder, in replacement of the centring opening 67. The        half-cylinder is oriented in such a manner that its central axis        is perpendicular to the large free face of the rail 49. Here;        the centring opening 87 opens onto the tongue 69 on the one        hand, and onto the large free face of the rail 49.    -   The openings 87 of two adjacent ends of rails 49 receive a        shared centring stud 89, of cylindrical shape, in replacement of        the hemispherical centring stud 65.    -   Each opening 87 is made in an insert 91, housed in the end face        of its respective rail 49. The insert 91 is configured as a wear        part.    -   Each rail 49 is equipped with a rack-and-pinion 93 which extends        along it, underneath the guide surface 64 and over the support        plate 53, on the external periphery of the rail 49.    -   The frame is equipped with hoist rings 95 which facilitate its        transport.    -   At least some of the crosspieces 7 are provided with an added        reinforcement rib 97, fixed by means of welding points 99, for        example.    -   At least some of the crosspieces 7 are provided with a hood 101        of sliding material of the type known as “NOFRIX”, for example,        to facilitate the passing of the ducts necessary for the        operation of the device.    -   A limit contactor 103 is provided behind each locking actuator        45 to ensure the correct locking of the latches.    -   Each clamping actuator is mounted on its respective plate by an        intermediary connecter board 105 equipped with a plurality of        radially offset fixation openings 107. This allows to adapt the        working position of the clamping actuators to different tube        diameters.    -   Some of the columns 65 are equipped with several, e.g. two,        resilient cylinders 57.    -   On FIG. 20, the clamping actuators 49 are shown without their        moving rod.

The invention is not limited to the embodiments described hereinbefore,solely by way of example, but encompasses all the variants that may beenvisaged by the skilled man, in particular:

-   -   each rail 49 may extend over an angular sector that is different        from that of the plate that supports it;    -   the support plate 53 is optional; the rail 49 may be attached        directly to the columns 55;    -   resilient cylinders 57 may be provided at the feet of the        columns 55, in addition to or instead of the resilient cylinders        57 arranged at the heads of these columns;    -   on the principle of the flange 5 described, flanges 5 of all        shapes and having any number of plates may be produced;    -   as described, the clamp 3 is particularly well suited to the        welding together of tubes to form a product of considerable        length such as a pipeline, for example.

The following process may be used:

-   -   one of the flanges 5 is clamped to an end portion of the long        product,    -   a tube is brought close to the end portion of the long product,        then the second flange 5 is clamped to the adjacent end portion        of the tube,    -   the holding actuators are actuated so as to align the tube and        the long product,    -   a welding bead is produced, by moving one or more tools.    -   for other applications, the clamp 3 may comprise only one flange        5, as shown in the alternative embodiment illustrated in FIG.        15;    -   the locking device may comprise only a single latch,        irrespective of the number of plates that make up the flange        that is to be locked;    -   the rail 49 may have a square-shaped section, and/or be tubular,        and/or have any other shape that permits guiding;    -   resiliently deformable supports for the rails 49 may be produced        in different forms, for example with springs, Belleville washers        and the like, instead of or in addition to the resilient        cylinders;    -   centring pins, for example three of them, which spread out so as        to engage the weld groove usually machined on the end face of        the tubes can be provided. They are advantageously arranged,        once spread out, at the level of the path of the welding torches        and/or of the tools moving on the guide track;    -   ball supports can be mounted on the flanges in order to        previously centre the frame, relieve the handling and/or        facilitate the sliding of the frame with respect to the tube.        For example, these ball supports permit to move the frame on a        tube manually, until the centring pins engage the weld groove of        said tube. The balls can be replaced by rollers.

1-13. (canceled)
 14. A device for assisting with working of mechanicalparts, comprising: a flange including at least two parts joined togetherwith an ability to move relative to one another in a common plane, up toa closed position of the flange in which the parts are joined together;a locking device that can be actuated in the closed position of theflange to bring the parts into mutual abutment; at least two rails; aset of resilient supports by which each rail is connected to at leastone respective part of the flange with limited scope for relativemovement; wherein adjacent end faces of the two rails includes matingsurfaces forming a connection by positive locking, the connection beingactive in a vicinity of the closed position; and each connection isconfigured to guide the adjacent end faces relative to one another in amovement relative to the parts, to a working position in which the railsform a guide path for one or more tools, to help keep these rails inmutual abutment, in the working position, when the locking device isactuated.
 15. A device according to claim 14, wherein the matingsurfaces comprise two complementary surfaces coming into mutual abutmentin the working position.
 16. A device according to claim 14, whereineach rail includes one or more guide surfaces and the connectioncomprises an arrangement configured to ensure continuity of the guidesurfaces in the working position.
 17. A device according to claim 16,wherein the arrangement comprises at least one tongue projecting from anend face of a rail and a groove provided in the adjacent end face of aneighbouring rail, the tongue and the groove both being of appropriatedimensions to fit into one another close to a position of closure of theflange.
 18. A device according to claim 17, wherein the tongue includesa portion whose cross-section becomes progressively narrower towards itsfree end.
 19. A device according to claim 16, wherein the arrangementcomprises at least one stud projecting from an end face of a rail and atleast one recess formed in the adjacent end face of a neighbouring rail,the stud and the recess both being of appropriate dimensions to fit intoone another close to a position of closure of the flange.
 20. A deviceaccording to claim 19, wherein the stud is at least partly hemisphericalor cylindrical in configuration.
 21. A device according to claim 14,further comprising a set of resilient parts intercalated between thesupports and their respective rails, in which the resilient parts aredeformed on actuation of the locking device and are arranged so thatthis deformation generates a contact pressure between the end surfacesof the rails at a predefined minimum level.
 22. A device according toclaim 21, wherein the resilient parts are arranged so that displacementof the rails relative to the parts of the flange takes place, at leastin the vicinity of the closed position, with deformation of at leastsome of the resilient parts.
 23. A device according to claim 21, whereinthe resilient parts are configured to each work with shear forces whenthe locking device is actuated.
 24. A device according to claim 21,wherein at least some of the resilient parts are in a form of a cylindermade of resilient material, and each cylinder is attached to one of thesupports and to a rail and/or a part of the flange.
 25. A deviceaccording to claim 14, wherein the flange is in a form of a flat crown.26. A device according to claim 14, wherein the guide path is of annularconfiguration.